1. Field of the Inventions
The inventions disclosed herein relate to a small jet propulsion watercraft on which an operator typically stands on a platform provided at a rear of the watercraft body (commonly known as “stand-up” type watercraft), and more particularly, to exhaust systems for such watercraft.
2. Description of the Related Art
Typically, stand-up type watercraft include a platform or “foot tray” provided at the rear of its hull for accommodating the operator. A jet pump is typically disposed below the foot tray. The jet pump is usually driven by a small internal combustion engine so as to draw in seawater from a bottom of the watercraft hull and to discharge the water from the stern of the hull, thereby providing thrust to propel the watercraft across a body of water. The engine on such a small jet propulsion watercraft is usually disposed such that its crankshaft extends longitudinally in the fore-to-aft direction of the body.
The engine usually has a plurality of cylinders, each having an intake port and an exhaust port. An intake system is connected to the intake port, and an exhaust system is connected to the exhaust port (see Japanese Patent Publication No. Hei 7-5219).
The exhaust system of this type of small jet propulsion watercraft typically has an exhaust pipe that is joined to the exhaust port of the engine and extends toward the front of the watercraft. An exhaust muffler is usually connected to the exhaust pipe, and a discharge pipe is typically connected to the exhaust muffler to discharge exhaust gas into the atmosphere. The exhaust pipe and the exhaust muffler are disposed inside of an engine chamber within the hull of the watercraft. In other small jet propulsion watercraft, an exhaust system is often includes a water lock device or other similar devices installed in a rear of the hull. In this case, too, most of the exhaust system is installed inside of the engine chamber or another chamber within the hull.